Motor

ABSTRACT

It is intended to suppress the vibration and noise during operation of a concentrated winding electric motor and to provide an electric motor with high efficiency, low vibration and low noise. A skew is formed on at least one of a stator ( 10 ) and a rotor ( 20 ), arranged with a concentrated winding, and a winding vibration damping body ( 18 ) is inserted between windings ( 13 ) of different phases within a winding groove ( 19 ) and contacted therewith.

TECHNICAL FIELD

The present invention relates to a concentrated winding motor having lownoise and low vibration and a hermetically enclosed compressor and thelike using the motor.

BACKGROUND ART

Conventionally concentrated winding motor used for compressors and thelike of air conditioners and refrigerators are configured as shown inFIGS. 10 to 12.

The concentrated winding motor is composed of a stator 60 and a rotor 80which is rotatively supported in the stator 60. The stator 60 shown inFIGS. 10 and 12 is constituted of laminated stator cores 61. The statorcore 61 is formed of teeth 62 provided with windings and a substantiallyannular yoke 64 for connecting the outer circumferences of the teeth 62.Tooth tip protrusions 65, which protrude in the circumferentialdirection along the inside diameter of the stator core, are formed onthe tips of the teeth 62.

In FIG. 10, the windings provided on the six teeth 62 on the stator core61 are represented by three-phase windings 63U, 63V, and 63W. Thedimensions and shapes of the three-phase windings 63U, 63V, and 63W arenot correctly indicated. Correct dimensions and shapes are shown in FIG.11 where winding is performed.

FIG. 11 is a sectional view taken along line X-X′ of FIG. 10. Windings63 representing the three-phase windings 63U, 63V, and 63W are providedon the teeth 62 of the stator core via an insulating material 67composed of an insulator which is formed into a film or is resin molded.

The three-phase windings 63U, 63V, and 63W are star connected with oneanother and have 120° rectangular wave conduction in which two of threephases are energized and driven at the same time. Further, an appliedvoltage is changed by PWM control.

Moreover, the stator cores 61 of this shape are laminated straight inthe axial direction without forming a skew thereon. Notches 66 formed onthe outer circumference of the stator core 61 act as through-holesbetween a shell 90 and the stator core 61 in the state in which thestator 60 is shrinkage-fitted to the shell 90 of a compressor. Thenotches 66 also act as passages for a refrigerant.

In the stator 60, the rotor 80 is rotatively held concentrically withrespect to the stator 60. The rotor 80 has permanent magnets 82 embeddedin a rotor core 81. End plates (not shown) are attached to both ends ofthe rotor core 81 and a rivet is passed through a through-hole providedin the rotor core, so that the end plates on both ends are fixed.Moreover, a shaft is provided in a shaft hole 83.

Therefore, due to a rotating magnetic field generated by current appliedto the three-phase windings 63U, 63V, and 63W which are provided on thestator 60, the rotor 80 is rotated about the shaft by torque which is acombination of magnet torque and reluctance torque.

As described above, in the case of the stator 60 in which a laminationis made straight without forming a skew, attracting or repellingstresses increase between the adjacent tooth tip protrusions 65, therebyincreasing vibrations as compared with distributed winding. Suchvibrations are considerably affected by a vibration in the radiusdirection as well as a vibration in a rotating direction.

Particularly in PWM control and 120° rectangular wave conduction inwhich only two of three phases are energized, vibrations areconsiderably increased. This is because current flowing into windingscontains more harmonics as compared with sine wave driving. Further, in120° rectangular wave conduction, a rapid change in current generatesstrong exciting force on the tooth tip protrusions, thereby increasingvibrations.

It is conventionally known that the formation of a skew is effective asa method for reducing variations in torque to have fewer vibrations. Askew is not formed only on the stator. For example, Japanese PatentLaid-Open No. 2000-175380 discloses that a skew is formed on a rotor oron both of a stator and the rotor. Vibrations generated in theconcentrated winding motor of FIG. 10 can be reduced by forming a skew.

However, in the case where variations in torque is reduced by forming askew on a stator and a stator core has ribs forming teeth on an annularinside diameter forming a yoke, the ribs are tilted by the skew. Theoccurrence of circular vibrations can be reduced but cannot becompletely eliminated only by skewing the stator. Further, it is foundthat windings stored in a noncontact manner in the same winding groovecause a mass with respect to generated slight circular vibration andthus vibrations are increased.

DISCLOSURE OF INVENTION

An object of the present invention is to suppress vibration and noiseduring an operation of a concentrated winding motor and to provide amotor having low vibration and low noise with high efficiency.

In order to solve the above-described problem, the motor of the presentinvention is configured so that a skew is formed on at least one of astator, which has concentrated windings, and a rotor, a windingvibration damping body is inserted between the windings in the windinggroove so as to come into contact with the windings directly or via aninsulating material, and the windings in the winding groove aresupported by the winding vibration damping body.

Further, when the number of poles is Np, a relative skew angle formed bythe stator and the rotor is set at 4° to (120/Np)°.

With this configuration, it is possible to realize a highly efficientmotor capable of suppressing vibration and noise during an operation theconcentrated winding motor.

A motor according to a first aspect 1 of the present invention comprisesa stator which has an annular yoke, a plurality of teeth arrangedsubstantially at regular intervals substantially in the radius directionon the inner circumference of the yoke, a winding groove between theadjacent teeth, and concentrated windings provided on each of the teeth,and a rotor that is opposed to the inner circumference of the statorwith a small clearance and is rotatively held, wherein a skew is formedon at least one of the stator and the rotor, and a winding vibrationdamping body is inserted between the windings in the winding groove.

With this configuration, even when the winding have a low space factor,the winding are supported by the winding vibration damping body in thewinding groove, so that the strength of the stator can be improved andthe vibration of the windings can be suppressed or damped. In the casewhere a skew is formed on the rotor as well as the stator, coggingtorque and a torque pulse can be reduced even when the stator forms asmaller skew angle.

A motor according to a second aspect of the present invention is themotor of the first aspect, wherein the winding vibration damping body ismade of a non-magnetic material or a material with a conductivity σ,where σ<1×10⁻⁵Ω⁻¹m⁻¹.

A motor according to a third aspect of the present invention is themotor of the first or second aspects, wherein the winding vibrationdamping body has a thermal expansion coefficient α, where α>1.1×10⁻⁵k⁻¹.With this configuration, the winding vibration damping body has a higherthermal expansion coefficient than a stator core, so that the teeth canbe held more firmly by heat generation during an operation of the motor.

A motor according to a fourth aspect of the present invention is themotor of any one of the first to third aspects, wherein the rotor haspermanent magnets embedded in a rotor core. With this configuration, itis possible to effectively use magnet torque caused by the permanentmagnets and reluctance torque caused by the saliency of the rotor.

A motor according to a fifth aspect of the present invention is themotor of the fourth aspect, wherein a rotor skew is formed on the rotorcore which is integrally formed by rotating rotor core units by a givenangle in the circumferential direction, the rotor core units havingmagnet embedding holes in the axial direction of the rotor and beingdivided into at least two in the axial direction of the rotor, thepermanent magnets being embedded in each of the magnet embedding hole.With this configuration, it is possible to reduce the leakage flux ofthe permanent magnets.

A motor according to a sixth aspect of the present invention is themotor of the fifth aspect, wherein the rotor core is divided in theaxial direction at regular intervals and the rotor core units are eachrotated in the circumferential direction at regular intervals. With thisconfiguration, the number of components can be reduced.

A motor according to a seventh aspect of the present invention is themotor of any one of the first to sixth aspects, wherein when the rotorhas Np poles, a relative skew angle formed by the stator and the rotoris 4° to (120/Np)°. With this configuration, it is possible to suppressthe circular vibration of the stator and rotor core. Further, when askew is formed on the stator and the rotor, a skew angle formed by thestator and the rotor can be smaller.

A motor according to an eighth aspect of the present invention is themotor of any one of the first to seventh aspects, wherein the winding iscomposed of a self-welding wire. With this configuration, it is possibleto improve the stiffness of the stator including the windings and thestator core.

A motor according to a ninth aspect of the present invention is suchthat the stator is formed by laminating stamped electromagnetic steelplates, and when a skew angle is θs and the number of the laminatedelectromagnetic plates is Ns, at least Ns small holes are provided, nearthe outer circumference of the stamped electromagnetic steel plates, onthe same circumference with a pitch of θh=θs÷Ns(°) relative to thecenter of rotation. With this configuration, the skew angle of thestator core can be readily fixed with accuracy.

A motor according to a tenth aspect of the present invention is themotor of any one of the first to eighth aspects, wherein the stator isformed by laminating stamped electromagnetic steel plates, and when askew angle is θs, a long hole is provided near the outer circumferenceof the stamped electromagnetic steel plates, the long hole extendingover an angle of θh=θs+α(°) on the same circumference with respect tothe center of rotation. With this configuration, the skew angle of thestator core can be readily fixed with accuracy.

A motor according to an eleventh aspect of the present invention is themotor of any one of the first to eighth aspects, wherein a grove or aprotrusion is formed on the outer circumference of the stator core and acylindrical frame is engaged in the stator core to form a skew, thecylindrical frame forming a protrusion or groove twisted by a skew anglein the axial rotating direction on the inner circumference to correspondto the groove or protrusion on the outer circumference of the statorcore. With this configuration, the skew angle of the stator can bereadily fixed with accuracy.

A hermetically enclosed compressor according to a twelfth aspect of thepresent invention comprises the motor according to any one of the firstto tenth aspects. With this configuration, it is possible to realize ahermetically enclosed compressor with low vibration and low noise.

A hermetically enclosed compressor according to a thirteenth aspect ofthe present invention is the compressor of the twelfth aspect, whereinthe stator of the motor forms notches acting as passages for arefrigerant on the outer circumference of the stator core, the outercircumference corresponding to the teeth. With this configuration, whilea magnetic path required for the passage of a magnetic flux is secured,though-holes can be formed between the shell of the compressor and thestator core when the stator is shrinkage-fitted to the shell of thecompressor.

A hermetically enclosed compressor according to the fourteenth aspect ofthe present invention uses the motor of the tenth aspect, and thecylindrical frame also acts as the shell of the hermetically enclosedcompressor. With this configuration, it is not necessary to use aspecial jig for forming a skew on the stator, thereby reducing thenumber of assembling steps.

A hermetically enclosed compressor according to a fifteenth aspect ofthe present invention is the compressor of any one of the twelfth tofourteenth aspects, wherein an HFC or a natural refrigerant is used as arefrigerant. With this configuration, an environmental load can bereduced.

A hermetically enclosed compressor according to a sixteenth aspect ofthe present invention is the compressor of any one of the twelfth tofifteenth aspects, wherein the terminals of the winding of the motor arefed with a voltage of 50 volts or lower. With this configuration, it ispossible to realize a hermetically enclosed compressor capable ofbattery driving with low vibration and low noise.

A refrigeration cycle according to the seventeenth aspect of the presentinvention uses the hermetically enclosed compressor according to any oneof the twelfth to sixteenth aspects. With this configuration, it ispossible to realize a refrigeration cycle with low vibration and lownoise.

An air conditioner according to an eighteenth aspect of the presentinvention uses the hermetically enclosed compressor according to any oneof the thirteenth to sixteenth aspects. With this configuration, it ispossible to realize an air conditioner with low vibration and low noise.

An automobile according to a nineteenth aspect of the present inventionis equipped with the air conditioner of the eighteenth aspect. With thisconfiguration, it is possible to realize an automobile with lowvibration and low noise.

An automobile according to a twentieth aspect of the present inventionis equipped with the motor according to any one of the first to tenthaspects as an actuator, and the terminals of the winging of the motor isfed with a voltage of 50 volts or lower. With this configuration, it ispossible to realize an automobile with low vibration and low noise.

A method of fabricating a motor according to a twenty-first aspect ofthe present invention is such that in fabricating the motor of the ninthaspect, the method includes: laminating the electromagnetic steel plateswhile displacing each of the small holes formed on the electromagneticsteel, and inserting a pin through the small holes of the laminatedelectromagnetic steel plates to fix the electromagnetic steel plates, sothat the stator is fabricated with a skew.

A method of fabricating a motor according to a twenty-second aspect ofthe present invention is such that in fabricating the motor of the tenthaspect, the method includes: inserting a pin through the long hole ofthe stamped electromagnetic steel plates to make a lamination, twistingan upper layer of the stator around the shaft center from a lower layerof the stator to form a skew on the stator, and performing fixation bywelding, bonding, or applying a pressure on the outer circumference ofthe laminated electromagnetic steel plates, so that the stator isfabricated.

A method of fabricating a hermetically enclosed compressor according toa twenty-third aspect of the present invention is such that infabricating the hermetically enclosed compressor using the motor of theeleventh aspect, a groove or a protrusion is formed on the outercircumference of the stator core and the stator core is engaged to theshell of the hermetically enclosed compressor of the cylindrical frame,the cylindrical frame forming a protrusion or groove twisted by a skewangle in the axial rotating direction on the inner circumference tocorrespond to the groove or the protrusion on the outer circumference ofthe stator core, thereby forming a skew.

A method of fabricating a hermetically enclosed compressor according toa twenty-fourth aspect of the present invention is such that infabricating the hermetically enclosed compressor using the motor of theeleventh aspect, the method includes: forming a groove or a protrusionon the outer circumference of the stator core, engaging the stator coreto a jig which is a cylindrical frame being dividable into at least twoor more in the circumferential direction and formed with a protrusion orgroove twisted by a skew angle in the axial rotating direction on theinner circumference so as to correspond to the groove or the protrusionon the outer circumference of the stator core so that a skew is formed,and detaching the stator having the formed skew from the jig andattaching the stator to the inside of the shell of the hermeticallyenclosed compressor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view showing a concentrated winding motoraccording to an embodiment of the present invention;

FIG. 2 is a perspective view showing a stator according to theembodiment;

FIG. 3 is a sectional view showing teeth and a winding groove of astator core according to the embodiment;

FIG. 4 is a characteristic diagram showing a displacement on the outercircumference of the stator core and a skew angle formed by the statorcore according to the embodiment;

FIG. 5 is a characteristic diagram showing a torque pulse and a skewangle according to the embodiment;

FIG. 6 is a perspective view showing a first method of fabricating astator constituting he motor of the present invention;

FIG. 7 is a perspective view showing a second method of fabricating thestator constituting the motor of the present invention;

FIG. 8 is a perspective view showing a third method of fabricating thestator constituting the motor of the present invention;

FIG. 9 is a diagram showing a rotor on which a skew is formed accordingto the present invention;

FIG. 10 is a sectional view showing a conventional concentrated windingmotor;

FIG. 11 is a sectional view showing teeth and a winding groove of astator core in the conventional concentrated winding motor; and

FIG. 12 is a perspective view showing the stator core in theconventional concentrated winding motor.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIGS. 1 to 9, the examples of the present invention will bedescribed below.

FIGS. 1 to 3 show a concentrated winding motor according to an exampleof the present invention. In a conventional concentrated winding motorshown in FIGS. 10 to 12, stator cores 61 are laminated straight in theaxial direction without forming a skew and thus ends 65 a along thecircumferential direction of the tooth tip protrusions 65 are formedalong a straight line extending in the axial direction. On the otherhand, in the present embodiment, ends 15 a along the circumferentialdirection of a tooth tip protrusion 15 of a stator core 11 are laminatedobliquely with respect to the axial direction, so that a skew is formed.

Further, winding on teeth is shown in FIG. 3. Windings 13 of differentphases are in contact with each other in a winding groove 19 with awinding vibration damping body 18 interposed between the windings 13.This winding state is different from the conventional state shown inFIG. 11 in which a clearance 100 is provided between the windings 63 ofdifferent phases in a winding groove.

Besides, regarding the stator structure, the connecting state ofthree-phase windings 13U, 13V, and 13W, and the conduction and drivingof the three-phase windings 13U to 13W, the present embodiment issimilar to the conventional art.

The details will be described below.

A motor of FIG. 1 that is used for a compressor of an air conditioner, arefrigerator, and the like is constituted of a stator 10 and a rotor 20.In the stator 10, the three-phase windings 13U, 13V, and 13W areprovided on six teeth 12 formed on the stator core 11. As shown in FIG.3, an insulating material 17 of a film and an insulator is interposedbetween the winding 13 and the stator core 11.

Notches 16 are formed on the outer circumference of the stator core 11.The notch 16 acts as a through-hole between a shell 90 and the statorcore 11 while the stator core 11 is shrinkage-fitted into the shell 90of the compressor. The notch 16 also acts as a passage for arefrigerant.

The rotor 20 disposed in a hole formed in the stator core 11 haspermanent magnets 22 embedded in a rotor core 21. Permanent magnets 22are not limited to those of FIG. 1. For example, a plurality of magnetsmay be disposed (embedded) like reversed arcs at least in one or morelayers.

FIG. 2 shows that a skew is formed on the stator 10 which is formed bylaminating the planar stator cores 11 of FIG. 1. Components other thanthe stator cores 11, for example, 13U, 13V, 13W and so forth which formthe winding 13 are not shown in FIG. 2.

The winding 13 can be fabricated by any method of nozzle winding, theinserter method, and a winding method of providing windings around theteeth 12 while passing the end of a copper wire (winding) through awinding groove on the top and underside of the stator core two or moretimes.

When the windings 13 are wound by nozzle winding, the windings can bearranged with an increased space factor and the axial length of a motorcan be reduced. On the other hand, when a skew is formed on the stator10 after winding, tension is applied to the windings 13 by forming theskew. However, the windings 13 are wound loosely beforehand or a spacehaving a length corresponding to the skew is provided on one or bothaxial end faces of the stator core 11, so that tension can be reduced.Further, when nozzle winding is performed on the laminated stator cores11, a space for moving a nozzle is necessary in the winding groove 19.When the windings 13, which are wound around the adjacent teeth 12 andare stored in the same winding groove 19, are not sufficiently incontact with each other within the predetermined skew angle, it ispreferable to use the winding vibration damping body 18.

Subsequently, when the windings 13 are provided by the inserter method,the width of an opening on the winding groove 19 (the width of aclearance between the adjacent tooth tip protrusions 15) can be smalleras compared with nozzle winding, so that the interlinkage of a magneticflux can be effectively obtained, a space factor can be improved, andthe motor can be more efficient. Moreover, in ordinary cases, thewinding 13 is temporarily wound larger than the width of the tooth tipprotrusion 15 before insertion and the winding 13 has an innercircumference longer than the outer circumference of the tooth 12 (fromthe tooth tip protrusion 15 to the outside diameter portion of thestator core 11). Thus, when the winding 13 is provided in the windinggroove 19, a space is formed between the axial end of the stator core 11and the inner circumference on the axial end of the winding 13. Evenwhen a skew is formed on the stator 10 after winding, tension is notapplied to the winding 13. Therefore, an advantage is obtained inproductivity and reliability.

Finally, in the case of the winding method of passing the end of acopper wire (winding 13) through the end of the winding groove 19 on thetop and the undersurface of the stator 11 so as to provide the windings13 around the teeth 12, since it is not necessary to insert the winding13 from the opening of the winding groove 19, it is possible to freelyset the size of the opening of the winding groove 19 and to readilyprovide arranged windings. Particularly since a skew is formed on thestator 10, winding can be performed even when the winding nozzle cannotenter from the opening on the inner circumference of the winding groove19 or when temporarily wound winding 13 cannot be inserted. This methodis effective especially when the number of times of winding is small,and this method is suitable for a thick wire and a flat wire.

The stator core 11 is constituted of the teeth 12 wound with thewindings 13, the tooth tip protrusions 15 which face the outercircumference of the rotor 20 and are usually disposed on the tips ofthe teeth 12 with a large width, and a substantially annular yoke 14 forconnecting the teeth 12.

FIG. 2 shows that a skew is formed on the stator 10 of FIG. 1. Here, inFIG. 2, parts other than the stator core 11, for example, the windings13 are omitted.

By forming a skew on the stator 10, it is possible to mainly reducevibrations caused by irregularities in torque.

However, noise and vibration are also caused by exciting force in theradius direction and a concentrated winding is particularly affected bythe forces of attraction between the adjacent teeth 12. Thus, vibrationscannot be reduced only by a skew.

Moreover, the notches 16 are formed on the outer circumference of thestator core 11. The notches 16 are formed on positions corresponding tothe teeth 12, that is on the same line as the teeth 12 (on a line in thediameter direction passing through the center of the stator core 12).The notches 16 form the same angle as the teeth 12.

FIG. 3 shows that a skew is formed on the stator 10 and the windings 13,which are wound around the adjacent teeth and are stored in the samewinding groove 19, are in contact with each other via the windingvibration damping body 18.

In the case where a skew is formed on the stator 10, according to a skewangle and an amount of the wound windings 13, the adjacent teeth 12 andthe windings 13 wound around the teeth 12 come into contact with eachother, from a certain skew angle, via the winding vibration damping body18 in the same winding groove 19. Thus, it is possible to improve thestrength of the stator 10 (stator core 11). Further, the windings 13increase the strength of the stator 10 which suppresses the vibration ofthe teeth 12. With the damper effect of the windings 13 making contactwith each other via the winding vibration damping body 18, it ispossible to suppress or damp the vibration of the teeth 12 and thewindings 13, thereby reducing the noise and vibration of the motor.

Particularly when the specification of the motor indicates a smallamount of windings (low space factor), the above-describedoperation/working effect can be readily achieved by inserting thewinding vibration damping body 18 between the windings 13.

Vibration can be suppressed by using, for the winding vibration dampingbody 18, a non-magnetic material or a material with a conductivity: σexpressed by the formula below:σ<1×10⁻⁵Ω⁻¹m⁻¹and a material having the above characteristic with a thermal expansioncoefficient: α expressed by the formula below:α>1.1×10⁻⁵k⁻¹

When the material with the conductivity: σ expressed by σ<1×10⁻⁵Ω⁻¹m⁻¹is used, it is possible to suppress the occurrence of induced currentwhich is caused by changes in magnetic flux appearing between theadjacent teeth 12, thereby reducing the vibration of the teeth 12 whilesuppressing Joule heating.

When the material with the thermal expansion coefficient expressed bythe formula α>1.1×10⁻⁵k⁻¹, with a thermal expansion coefficient largerthan that of an iron material constituting the stator core 11, the teeth12 can be held more firmly by heat generated during the operation of themotor, thereby further suppressing the vibration of the teeth 12. Thiseffect is enhanced particularly when the material is used at a hightemperature.

By using a resin molded product of PPS, PET, PBT, PA, PTFE, and so onfor the non-magnetic winding vibration damping body 18, it is expectedthat the stiffness of the stator 10 is improved and the effect ofdamping vibration is obtained. These polyester resins are suitableparticularly in a refrigerant of a hermetically enclosed compressor andthe like.

Besides, the windings 13 are preferably wound around the teeth 12 viathe insulating material 17 (insulating film, an insulator, and thelike). Particularly in a refrigerant of a hermetically enclosedcompressor and the like, a polyester film is preferable as theinsulating material 17. To be specific, an HFC may be used as therefrigerant. A natural refrigerant is also applicable.

When a film is used to insulate the stator core 11 and the windings 13,in order to acquire a space insulation distance between the coil end andthe axial end face of the stator core 11, it is preferable to fold bothaxial ends of the film with a predetermined width and to hang the axialends on the ends of the stator core 11. Further, the windings 13 havingdifferent phases in the same winding groove 19 maybe insulated from eachother at the same time by providing, along the winding groove 19, a filmwhich insulates the stator core 11 and the windings 13 and extending theends of the film.

Further, the stator 11 and the windings 13 maybe insulated by using aninsulator which is molded of a resin and is provided along the windinggroove 19.

Additionally, the insulating material 17 may be inserted between thewinding 13 and an insulating support member 18.

FIG. 4 shows the relationship between a displacement on the outercircumference of the stator core (exciting force during the operation ofthe motor is set at the inside diameter of the stator) and a skew angleformed on the stator core. FIG. 5 shows the relationship between atorque pulse and a skew angle.

According to FIG. 4, when the stator core 11 is assumed to have, on itsannular internal side forming the yoke, protrusions forming the teeth,that is ribs, the ribs are not provided straight in the axial directionbut are twisted with a skew angle of 4° or larger in the circumferentialdirection, so that circular vibration is suppressed.

FIG. 4 shows a displacement on the outer circumference of the statorrelative to a given constant load. For example, the line of FIG. 4 movesvertically according to an increase and a reduction in load. At anyload, the skew angle is 4° and the displacement remains constant.

Further, according to FIG. 5, it is confirmed that when the number ofpoles of the rotor 20 is Np=4, a torque pulse increases at a skew angleof 30 (120/Np)° or larger.

Therefore, by setting the skew angle at 4° to (120/Np)°, it is possibleto increase the natural frequency of the circular vibration and reducethe displacement of the vibration of the stator core while reducing atorque pulse, achieving lower vibration and noise during an operation.

The windings 13 are formed as self-welding wires and are fixed byapplying heat and power to the windings 13 after a skew is formed on thestator 10, so that the windings 13 of the same phase are brought intocontact and are fixed with each other more firmly in the winding groove19. Thus, the vibration of the windings 13 can be suppressed.

The following will describe the formation of a skew that is applicableto the stator of the motor according to the present invention.

Two methods are available for forming a skew on the stator 10.

In one of the methods, a skew is formed after winding (including theinsertion of the windings 13 according to the inserter method, thisapplies in the following explanation). In the other method, winding isperformed after a skew is formed on the stator 10.

In the former case, the opening of the winding groove 19 is formedstraight along the axial direction and thus winding can be readilyperformed, achieving high productivity.

In the latter case, winding is performed while the stator core 11 isskewed. Thus, when a skew is formed on the stator 10 after winding, itis possible to fabricate the motor with excellent insulation withoutdamaging the windings 13.

FIG. 6 shows a specific example of forming a skew on the stator 10.

When the skew angle is θs and the number of laminated electromagneticsteel plates 40 is Ns, Ns small holes 41 are provided at least on thesame circumference with a pitch of θh relative to the center ofrotation, near the outer circumference of the stator core 11 composed ofstamped electromagnetic steel plates. θh is expressed by θh=θs÷Ns(°).

A skew is formed on the stator 10 while displacing each of the smallholes 41, and pins 31 are passed through the small holes 41 to fix thestator core 11, so that the skew angle of the stator core 11 is readilydetermined with accuracy and fixation is performed.

For example, in the case of a groove for 4 poles and 6 windings, when askew of 15° is formed and 80 electromagnetic steel plates 40, eachhaving a thickness of 0.5 mm, are laminated to have a total thickness of40 mm, it is preferable to provide 80 small holes with a pitch ofθh=15÷80=0.1875°. Such small holes are particularly applicable to, forexample, a compressor and the like with a large capacity in a packagedair conditioner. Further, when these holes are provided so as to besymmetric by 180°, the skewing process can be performed in a morepositive manner. Moreover, after the pins 31 are passed through thesmall holes 41, the layers may be fixed with each other by welding,bonding, or applying a pressure (swaging) on the outer circumference ofthe stator 10. In this case, even when the windings 13 have a hightension, it is possible to keep the fixation between the layers of thestator core 11.

In such a fabricating method, when the number of laminated layers isdifferent, the stator core 11 cannot be used with the same stampedshape. This point can be improved by a fabricating method shown in FIG.7.

In the fabricating method of FIG. 7, instead of the small holes 41 ofFIG. 6, a long hole 42 extending on the same circumference is providedover an angle of θh=θs+α(°) (α is an angle corresponding to the width ofa pin) with respect to the center of rotation. In the state in which apin 32 is inserted through the long hole 42, an laminated upper layer istwisted from a lower layer around the shaft center in the stator core 11so as to form a skew on the stator 10. Thereafter, the laminated layersare fixed by welding, bonding, or applying a pressure (swaging) on theouter circumference of the laminated stator cores 11, so that the skewangle of the stator core 11 can be precisely determined and fixation isperformed.

In this way, even when the lamination is changed, the same stamped shapecan be used and the shared use of components is allowed. Besides, inFIG. 7, only one long hole 42 is provided in the circumferentialdirection of the stator core 11. Two or more long holes 42 may beprovided.

FIG. 8 shows another specific example of forming a skew on the stator10.

In FIG. 8, elements such as the windings 13 constituting the stator 10are omitted.

A groove 43 is provided on at least one position of the outercircumference of the stator core 11. Before a skew is formed, the groove43 is aligned on the same position. The inside of the shell 90 fit intothe outside of the stator core 11 comprises a protrusion 51 which istwisted by a predetermined skew angle in the axial rotating direction soas to correspond to the position of the groove 43. When the stator core11 is stored in the shell 90, a skew is formed on the stator 10.

Such a fabricating method can readily form a skew on the stator 10,increasing productivity. In this case, the stator core 11 may be formedby press fitting or shrink fitting. However, since the stampedelectromagnetic steel plates are not firmly fixed to each other, a smallinterference is desirable. Further, in the case of loose fitting, a unitfor fixing the shell 90 and the stator core 11 is necessary.

In the above explanation, the shell 90 fit into the outside of thestator core 11 is the shell of a compressor. Hence, a special jig forforming a skew on the stator 10 is not necessary and the shell 90 can beused as a component as it is, so that used materials can be reduced, theproductive facilities can be simplified, and productivity is improved.

The following configuration is also applicable: before the stator 10 isstored in the shell 90, a jig is used which is cylindrical as the shell90, can be divided into at least two or more in the circumferentialdirection, and comprises the protrusion 51 twisted by a predeterminedskew angle in the axial rotating direction on the inner circumference soas to correspond to the position of the groove 43, the stator 10 isformed with a skew formed by the jig, and the stator 10 is stored in theshell 90.

The above explanation described the case where a skew is formed on thestator 10. Also when a skew is formed on the rotor 20 having permanentmagnets embedded as shown in FIG. 1, an advantageous operation/workingeffect can be obtained as compared with the rotor suppressing thevibration of the motor or having no skew.

Further, since a skew angle is a relative angle formed by the stator 10and the rotor 20, when a skew is formed on the rotor 20, it is possibleto reduce a skew angle formed on the stator 10, thereby readilyfabricating the stator 10. A relative angle is 4° to (120/Np)° then, andthe tilting direction of a skew on the stator 10 and the tiltingdirection of a skew on the rotor 20 are formed in opposite directions.

In the above examples, the groove 43 is formed on the stator core 11 andthe protrusion 51 engaged in the groove 43 is formed on the shell 90 orthe jig. The same configuration is made also by forming a protrusion onthe stator core 11 and forming a groove, which is engaged to theprotrusion on the stator core 11, on the shell 90 or the jig.

In the above examples, the shell 90 attached with the stator core 11 isthe shell 90 of a hermetically enclosed compressor. A shell of a motorused as the actuator for various apparatuses is similarly applicable.

FIG. 9 shows the rotor 20 having a skew formed thereon.

The rotor 20 having a skew formed thereon is constituted of rotor coreunits 21A and 21B which are divided into two in the axial direction ofthe rotor 20. The rotor core units 21A and 21B each comprise magnetembedding holes 23 in the axial direction of the rotor 20.

The rotor core unit 21A and the rotor core unit 21B have permanentmagnets 22A and 22B embedded in the magnet embedding holes 23, and areconstituted of the rotor core 21 which is displaced by rotation of agiven angle in the circumferential direction and is integrally formed.

With this configuration, although the permanent magnets 22A and 22B arevertically divided in the rotor 20, when projection is performed fromthe end face of the rotor 20, an arrangement is made like a letter X.For example, a magnetic flux flows from one side on the permanent magnet22A (e.g. north pole) to the other side on the permanent magnet 22B(south pole when the side on the permanent magnet 22A is the northpole), thereby reducing leakage flux.

Further, a skew may be formed continuously on the rotor 20 as theformation of a skew on the stator 10. In this case, when it is assumedthat the permanent magnets 22A and 22B are resin magnets permittinginjection molding, the fabrication can be readily performed.

In FIG. 9, the rotor core 21 is constituted of the two rotor core units21 and 21B. The rotor core 21 only has to be divided into at least twoin the axial direction of the rotor 20 and be integrally formed whilebeing displaced by rotation of a given angle in the circumferentialdirection.

In the above examples, a skew is formed on the stator 10 or both of thestator 10 and the rotor 20. A skew may be formed only on the rotor 20.

Besides, these motors can be used for the actuator of a mobile unit(e.g., an automobile, an electric wheelchair, an electric bicycle, or anelectric catering wagon) and the refrigeration cycle of an airconditioner installed in the mobile unit, as well as a hermeticallyenclosed compressor. Also when driving is performed by a battery mountedin the same mobile unit, since the motor is highly efficient, the powerconsumption of the battery can be reduced. Moreover, since the motor ishighly efficient, the motor required to obtain the same output can bereduced in size as compared with the conventional art.

Moreover, when a power supply for operating the motor is a battery, thatis when a voltage applied across the terminals of the winding of themotor is 50 volts or lower, for example, 12, 24, or 42 volts, since themotor is highly efficient, the power consumption of the battery can bereduced and the motor can operate for many hours.

As described above, according to the present invention, a skew is formedat least one of the stator and the rotor and the winding vibrationdamping body is inserted between the windings in the winding groove ofthe stator, thereby improving the strength of the stator, suppressing ordamping the vibration of the teeth and the windings, and achieving lowvibration and low noise. Moreover, particularly even when a space factoris low, the windings in the winding groove can be readily supported.

Further, since the rotor has the permanent magnets embedded in the rotorcore, it is possible to effectively use magnet torque produced by thepermanent magnets and reluctance torque produced by the saliency of therotor, increasing the efficiency of the motor. Further, since a skew isformed on the rotor, cogging torque and a torque pulse can be reducedand the stator forms a smaller skew angle. Moreover, the rotor skew isformed while the permanent magnets are embedded into the stator corewhich is integrally formed by rotating the stator core units, which aredivided into at least two in the rotor axial direction, by a given anglein the circumferential direction. Thus, it is possible to reduce leakageflux and improve efficiency.

Moreover, regarding the skew angle, when the number of poles is Np, arelative skew angle formed by the stator and the rotor is 4° to(120/Np)°, so that circular vibration is suppressed, a natural frequencyis increased, a displacement in the vibration of the stator core isreduced, and vibration and noise can be reduced during an operation.Additionally, when a skew is formed on both of the stator and the rotor,it is possible to reduce a skew angle formed by each of the stator andthe rotor, thereby improving productivity.

Besides, since the self-welding wire is used, it is possible to improvethe stiffness of the stator including the windings, further suppressingor damping the vibration of the windings.

Additionally, regarding the stator, a skew is formed while the smallholes, which are provided with a pitch of θh=θs÷Ns(°) near the outercircumference of the stamped electromagnetic steel plates, are displacedone by one, and the pin is inserted through the small hole provided nearthe outer circumference of the electromagnetic plates. Alternatively,one or more long holes extending on the same circumference are providedover an angle θh=θs+α(°) (α is an angle corresponding to the width ofthe pin) with respect to the center of rotation, a skew is formed on thestator while the pin is inserted through the long hole, and thelaminated electromagnetic plates are fixed by welding, adhesion, orapplying a pressure on the outer circumference of the stator core, sothat the skew angle of the stator core can be readily formed withaccuracy.

Further, the motor of the present invention having the unique effect isused for a hermetically enclosed compressor or a car actuator, and thehermetically enclosed compressor is used for the refrigeration cycle, anair conditioner, or an automobile. Hence, these apparatuses can have lowvibration and low noise.

Furthermore, in the motor for the hermetically enclosed compressor usedfor these apparatuses, the notches acting as passages for a refrigerantare formed on the outer circumference corresponding to the teeth of thestator core. Hence, it is possible to secure a magnetic path requiredfor the passage of a magnetic flux, thereby suppressing a reduction inthe efficiency of the motor.

1. A motor, comprising: a stator having an annular yoke, a plurality ofteeth arranged substantially at regular intervals substantially in aradius direction on an inner circumference of the yoke, a winding groovebetween the adjacent teeth, and a concentrated winding provided on eachof the teeth; a winding vibration damping body having a single solidcross-section, which body is located in the winding groove so that saidadjacent windings are in contact with each other via the windingvibration damping body; and a rotor for rotation about an axis ofrotation, said rotor opposing an inner circumference of the stator witha small clearance therebetween, wherein at least the stator comprises awinding having a skew, and opposing surfaces of said damping body aresubstantially parallel to planes defined by an outer envelope of each ofsaid adjacent windings and to the skew.
 2. The motor according to claim1, wherein the winding vibration duping body comprises a non-magneticmaterial or a material having a conductivity σ, where σ<1×10⁻⁵Ω⁻¹m⁻¹. 3.The motor according to claim 1, wherein the winding vibration dampingbody has a thermal expansion coefficient α, where α>1.1×10⁻⁵k⁻¹.
 4. Themotor according to claim 1, wherein the rotor has a permanent magnetembedded in a rotor core.
 5. The motor according to claim 4, wherein arotor skew is formed on the rotor cores integrally formed by rotatingrotor core units by a given angle in a circumferential direction, therotor core units having magnet embedding holes in an axial direction ofthe rotor and being divided into at least two in the axial direction ofthe rotor, the permanent magnet being embedded in each of the magnetembedding hole.
 6. The motor according to claim 5, wherein the rotorcore is divided in the axial direction at regular intervals and therotor core units are each rotated in the circumferential direction atregular intervals.
 7. The motor according to claim 1, wherein when therotor has Np poles in number, a relative skew angle formed by the statorand the rotor is in a range of 40° to (120/Np)°.
 8. The motor accordingto claim 1, wherein the winding comprises a self-welding wire.
 9. Themotor according to claim 1, wherein the stator is formed by laminatingstamped electromagnetic steel plates, and when a skew angle is θs andthe number of the laminated electromagnetic plates is Ns, at least Nssmall holes are provided, near an outer circumference of the stampedelectromagnetic steel plates, on a same circumference with a pitch ofθh=θs÷Ns(°) relative to a center of rotation.
 10. A method offabricating a motor, wherein in fabricating the motor of claim 9, themethod comprises: laminating the electromagnetic steel plates whiledisplacing each of the small holes formed on the electromagnetic steel,and inserting a pin through the small holes of the laminatedelectromagnetic steel plates to fix the electromagnetic steel plates, sothat the stator is fabricated with a skew.
 11. The motor according toclaim 1, wherein the stator is formed by laminating stampedelectromagnetic steel plates, and when a skew angle is θs, a long holeis provided near an outer circumference of the stamped electromagneticsteel plates, the long hole extending over an angle of θh=θs+α(°) on asame circumference with respect to a center of rotation.
 12. Ahermetically enclosed compressor, wherein the compressor uses the motorof claim 11, and the cylindrical frame also acts as a shell of thehermetically enclosed compressor.
 13. A method of fabricating a motor,wherein in fabricating the motor of claim 11, the method comprises:inserting a pin through the long hole of the stamped electromagneticsteel plates to make a laminations; twisting an upper layer of thestator around the shaft center with respect to a lower layer of thestator to form a skew on the stator; and performing fixation by welding,bonding, or applying a pressure on an outer circumference of thelaminated electromagnetic steel plates, so that the stator isfabricated.
 14. The motor according to claim 1, wherein a grove or aprotrusion is formed on an outer circumference of the stator core and acylindrical frame is engaged in the stator core so as to form a skew,the cylindrical frame forming a protrusion or groove twisted by a skewangle in an axial rotating direction on an inner circumference so as tocorrespond to the groove or the protrusion on the outer circumference ofthe stator core.
 15. A method of fabricating a hermetically enclosedcompressor, wherein in fabricating the hermetically enclosed compressorusing the motor of claim 14, a groove or a protrusion is formed on theouter circumference of the stator core and the stator core is engaged toa shell of the hermetically enclosed compressor of a cylindrical frame,the cylindrical frame forming a protrusion or groove twisted by a skewangle in an axial rotating direction on an inner circumference so as tocorrespond to the groove or the protrusion on the outer circumference ofthe stator core, thereby forming a skew.
 16. A method of fabricating ahermetically enclosed compressor, wherein in fabricating thehermetically enclosed compressor using the motor of claim 14, the methodcomprises: forming a groove or a protrusion on the outer circumferenceof the stator core; engaging the stator core to a jig that is acylindrical frame being dividable into at least two in a circumferentialdirection and formed with a protrusion or groove twisted by a skew anglein an axial rotating direction on an inner circumference so as tocorrespond to the groove or the protrusion on the outer circumference ofthe stator core, so that a skew is formed; and detaching the statorhaving the formed skew from the jig and attaching the stator to aninside of the shell of the hermetically enclosed compressor.
 17. Ahermetically enclosed compressor, comprising the motor according toclaim
 1. 18. The hermetically enclosed compressor according to claim 17,wherein the stator of the motor has a notch formed on the outercircumference of the stator core, the notch acting as a passage for arefrigerant, the outer circumference corresponding to the teeth.
 19. Anair conditioner, wherein the air conditioner uses the hermeticallyenclosed compressor according to claim
 18. 20. An automobile, whereinthe automobile is equipped with the air conditioner of claim
 19. 21. Thehermetically enclosed compressor according to claim 17, wherein an HFCor a natural refrigerant is used as a refrigerant.
 22. The hermeticallyenclosed compressor according to claim 17, wherein terminals of thewinding of the motor are fed with a voltage of 50 volts or lower.
 23. Arefrigeration cycle, wherein the cycle uses the hermetically enclosedcompressor according to claim
 17. 24. An automobile, wherein theautomobile is equipped with the motor according to claim 1 as anactuator, and terminals of the winging of the motor are fed with avoltage of 50 volts or lower.